A Note on Confidence Intervals for Hazard Ratio

조건호,최명희 慶山大學校 1995 論文集 Vol.13 No.1

생존분석(Survival analysis)에서 두집단을 비교할 매 위험함수(Hazard function)의 비율인 위험비(Hazard ratio)를 이용한다. 이 논문에서는 커넬위험비추정량(Kernel hazard ratio estimator)의 분산의 추정량에 대한 균일일치성(Uniform consistency)을 셈과정(Counting process)을 이용하여 증명하고, 위험비에 대한 신뢰구간(Confidence interval)과 Log-mimus-log와 Arcsine-square root 변환의 신희구간과 붓스트랩신뢰구간(Bootstrap confidence interval)을 유도하고 이러한 신뢰구간들을 몬테칼로 모의실험(Monte Carlo simulation)을 통하여 Achieved error rates로 비교·분석한다. The uniform consistency of variance estimator of kernel hazard ratio estimator is proved by using counting process approach. Pointwise confidence intervals for hazard ratio based on the log-minus-log and arcsine-square root transformations and bootstrap confidence intervals for hazard ratio are considered. Comparisons of confidence intervals are given by the achieved error rates of confidence intervals through Monte Carlo simulation.

Model Checking for Binary Response Data : Beetle Mortality Example

하일도,조건호,최명희 慶山大學校 1997 論文集 Vol.15 No.1

본 논문은 통계패키지 GENSTAT macro에 근거한 K-system(1996)에서 제공해주는 모형검토를 활용하여, Bliss(1935)에 의해 소개된 딱정벌레 사망율자료(Beetle mortality data)에 대한 적절한 모형을 찾는 방법을 연구한다.

Effects of deep sea water on the growth of the young sporophytes of Undaria pinnatifida

Geon-Hui Choi,Nam-Gil Kim 한국수산과학회 양식분과 2021 한국수산과학회 양식분과 학술대회 Vol.2021 No.4

다발성골수종 환자의 건강증진행위에 영향을 미치는 요인

최건희(Choi, Geon-Hui),강희영(Kang, Hee-Young) 기본간호학회 2011 기본간호학회지 Vol.18 No.2

Purpose: The purpose of this study was to analyzing the relationship between perceived health status, health locus of control, self-esteem, self-efficacy and HPB in patients with multiple myeloma to identify factors influencing health promoting behavior (HPB). Methods: One hundred patients were recruited into the study. The data were collected by personal interviews using questionnaires. Descriptive statistics, Pearson’s correlation coefficients and stepwise multiple regression analysis were used with SPSS program to were analyze the data. Results: There were significant relationships between self-esteem (r=.787, p<.001), self-efficacy (r=.681, p<.001), internal health locus of control (r=.557, p<.001), powerful others health locus of control (r=.517, p<.001), chance health locus of control (r=-.251, p=.012), perceived health status (r=.532, p<.001) and HPB. Significant factors in explaining HPB were self-esteem, powerful others health locus of control, self-efficacy and perceived health status and together they accounted for 71% of variance. Conclusion: The study findings indicate that self-esteem, powerful others health locus of control, self-efficacy, and perceived health status were important factors in explaining HPB in patients with multiple myeloma. As self-esteem was an important variable in HPB, health promotion program designed for this population should focus on self-esteem and these other factors to enhance effective health promotion behavior.

모자(Hat)형 보강재를 가진 복합재 패널의 제작과 평가

김건희 ( Geon Hui Kim ),임도완 ( Do Wan Lim ),최진호 ( Jin Ho Choi ),권진회 ( Jin Hwe Kweon ),이태주 ( Tae Joo Lee ),송민환 ( Min Hwan Song ),신상준 ( Sang Joon Shin ) 한국복합재료학회 2010 Composites research Vol.23 No.2

Oral Delivery of Probiotics in Poultry Using pH-Sensitive Tablets

( Tao Jiang ),( Hui-shan Li ),( Geon Goo Han ),( Bijay Singh ),( Sang-kee Kang ),( Jin-duck Bok ),( Dae-duk Kim ),( Zhong-shan Hong ),( Yun-jaie Choi ),( Chong-su Cho ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.4

As alternatives to antibiotics in livestocks, probiotics have been used, although most of them in the form of liquid or semisolid formulations, which show low cell viability after oral administration. Therefore, suitable dry dosage forms should be developed for livestocks to protect probiotics against the low pH in the stomach such that the products have higher probiotics survivability. Here, in order to develop a dry dosage forms of probiotics for poultry, we used hydroxypropyl methylcellulose phthalate 55 (HPMCP 55) as a tablet-forming matrix to develop probiotics in a tablet form for poultry. Here, we made three different kinds of probiotics-loaded tablet under different compression forces and investigated their characteristics based on their survivability, morphology, disintegration time, and kinetics in simulated gastrointestinal fluid. The results indicated that the probiotics formulated in the tablets displayed higher survival rates in acidic gastric conditions than probiotics in solution. Rapid release of the probiotics from the tablets occurred in simulated intestinal fluid because of fast swelling of the tablets in neutral pH. As a matrix of tablet, HPMCP 55 provided good viability of probiotics after 6 months under refrigeration. Moreover, after oral administration of probiotics-loaded tablets to chicken, more viable probiotics were observed, than with solution type, through several digestive areas of chicken by the tablets.

A holey graphene-based hybrid supercapacitor

Jeong, Jun Hui,Lee, Geon-Woo,Kim, Young Hwan,Choi, Yeon Jun,Roh, Kwang Chul,Kim, Kwang-Bum Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.378 No.-

<P><B>Abstract</B></P> <P>Holey graphene with nano-sized holes has numerous electrochemically active sites and an open porous structure, imparting a higher electrocatalytic activity and faster electron and ion transport compared with basal planes in graphene. In this study, holey graphene-based electrode materials, prepared using holey graphene as building blocks, are applied in both electric double-layer capacitor- and lithium-ion battery-type electrodes, because holey graphene possesses more electrochemically active sites originating from the edge sites and facilitates faster electron/ion transport through the holes. The enhanced specific capacity of holey graphene can be attributed to its edge sites, because an additional electric double-layer is formed at the edges. The enhanced rate capability of the Li<SUB>4</SUB>Ti<SUB>5</SUB>O<SUB>12</SUB>/holey graphene composite can be attributed to the in-plane holes, because they enhance lithium-ion transport across the graphene to Li<SUB>4</SUB>Ti<SUB>5</SUB>O<SUB>12</SUB>. We successfully design a hybrid supercapacitor consisting of holey graphene and the Li<SUB>4</SUB>Ti<SUB>5</SUB>O<SUB>12</SUB>/holey graphene composite. The hybrid supercapacitor delivers a maximum energy density of 117.3 Wh·kg<SUP>−1</SUP> at a power density of 0.1 kW·kg<SUP>−1</SUP>, and a maximum power density of 19.7 kW·kg<SUP>−1</SUP> is achieved at an energy density of 43.1 Wh·kg<SUP>−1</SUP>. The outstanding energy and power density demonstrate the increased specific capacitance of the capacitor-type electrode and rate capability of the battery-type electrode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HG-based materials introduced in-plane hole were synthesized for high-performance HSC. </LI> <LI> HSC consisting of spherical HG (cathode) and spherical LTO/HG (anode) was designed. </LI> <LI> Edges improve specific capacitance of spherical HG by forming additional EDL. </LI> <LI> Holes improve rate capability of spherical LTO/HG by enhancing lithium ion transport. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Rational design of oxide/carbon composites to achieve superior rate-capability <i>via</i> enhanced lithium-ion transport across carbon to oxide

Jeong, Jun Hui,Kim, Myeong-Seong,Choi, Yeon Jun,Lee, Geon-Woo,Park, Byung Hoon,Lee, Suk-Woo,Roh, Kwang Chul,Kim, Kwang-Bum The Royal Society of Chemistry 2018 Journal of materials chemistry. A, Materials for e Vol.6 No.14

<P>Coating oxides with conductive carbon is a widely used strategy to improve the rate capability of oxides by enhancing their electronic conductivity. However, there is a growing concern that a carbon layer may hinder lithium-ion transport to oxides, thus limiting the rate capability. Nonetheless, this issue has not yet been thoroughly investigated, and whether lithium-ion transport across a carbon layer does indeed limit the rate capability remains unclear. To single out the effect of lithium-ion transport across a carbon layer on the rate capability, we propose the rational design and synthesis of nano-perforated graphene (NPG)-wrapped oxide composites using commercial Li4Ti5O12 (LTO) and LiFePO4 (both with a particle diameter of ∼70 nm), wherein the NPG has nano-perforations on the basal plane of graphene. As the number of nano-perforations in the composites increases, the rate capability significantly increases. For example, NPG-wrapped LTO shows a specific capacity of 117.9 mA h g<SUP>−1</SUP> at 100C and could be stably charged-discharged even at 300C. The excellent rate capability is mainly due to the enhancement of lithium-ion transport through the nano-perforations of NPG. Cyclic voltammetry and impedance analyses reveal that the improved rate capability of NPG-wrapped LTO is closely associated with an increase in the area of electrochemically active sites of LTO in the composite due to the enhanced lithium-ion transport through the nano-perforations of NPG, indicating that lithium-ion transport across a carbon layer could limit the rate capability of oxides coated with highly conductive carbon. These salient results will provide further impetus to the design and synthesis of novel high-rate carbon-coated oxides.</P>

Study of Brittle Crack Propagation Welding for EH40 Steel Plate in Shipbuilding Steel

Kyung-Shin Choi(최경신),Sang-Hoon Lee(이상훈),Won-Jee Chung(정원지),Hui-Geon Hwang(황희건),Seok-Han Hong(홍석한),Ji-Ung Hong(홍지웅) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.5

Recent economic trends are worsening and becoming longer, and Korean shipbuilding is focused on high value added and high technology, especially for LNG carriers and large container ships. Both ship types increased in size in the 2010s but have requirements such as high strength, toughness at low temperatures and continuous weldability for preventing brittle fractures at service temperatures. In particular, as container ships become larger, the International Classification Society (IACS) has established a provision (IACS UR S33) that mandates the use of BCA (Brittle Crack Arrest) certified vessels for large container vessels contracted after 2014 to ensure safety. Therefore, studies on BCA 47Y.P are currently being undertaken, but BCA 40Y.P has not been actively studied yet. We will test BCA 40Y.P to verify why it can be applied to a large container ship and measure fatigue cracking.

Magnesium phosphate ceramics incorporating a novel indene compound promote osteoblast differentiation <i>in vitro</i> and bone regeneration <i>in vivo</i>

Kim, Ju Ang,Yun, Hui-suk,Choi, Young-Ae,Kim, Jung-Eun,Choi, So-Young,Kwon, Tae-Geon,Kim, Young Kyung,Kwon, Tae-Yub,Bae, Myung Ae,Kim, Nak Jeong,Bae, Yong Chul,Shin, Hong-In,Park, Eui Kyun IPC Science and Technology Press 2018 Biomaterials Vol.157 No.-

<P><B>Abstract</B></P> <P>Incorporating bioactive molecules into synthetic ceramic scaffolds is challenging. In this study, to enhance bone regeneration, a magnesium phosphate (MgP) ceramic scaffold was incorporated with a novel indene compound, KR-34893. KR-34893 induced the deposition of minerals and expression of osteoblast marker genes in primary human bone marrow mesenchymal stem cells (BMSCs) and a mouse osteoblastic MC3T3-E1 cell line. Analysis of the mode of action showed that KR-34893 induced the phosphorylation of MAPK/extracellular signal-regulated kinase and extracellular signal-regulated kinase, and subsequently the expression of bone morphogenetic protein 7, accompanied by SMAD1/5/8 phosphorylation. Accordingly, KR-34893 was incorporated into an MgP scaffold prepared by 3D printing at room temperature, followed by cement reaction. KR-34893-incorporated MgP (KR-MgP) induced the expression of osteoblast differentiation marker genes <I>in vitro</I>. In a rat calvaria defect model, KR-MgP scaffolds enhanced bone regeneration and increased bone volume compared with MgP scaffolds, as assessed by micro-computed tomography and histological analyses. In conclusion, we developed a method for producing osteoinductive MgP scaffolds incorporating a bioactive organic compound, without high temperature sintering. The KR-MgP scaffolds enhanced osteoblast activation <I>in vitro</I> and bone regeneration <I>in vivo</I>.</P>